1. Field of the Invention
The present invention relates to a method of diagnosing a combustion state in a combustion furnace, for example, the furnace of a boiler for power generation.
It is very important for burning to hold a combustion state good. The good combustion state is realized by such important factors as utilizing fuel effectively, namely, attaining a high combustion efficiency, and reducing poisonous components to be contained in emitted smoke, to the utmost.
2. Description of the Prior Art
In knowing a combustion state from a flame inside a boiler furnace, there have heretofore been performed, for example, a method wherein the flame during burning is directly viewed with an ITV (industrial television) set which is mounted on a wall opposite a burner nozzle, and a method wherein the flame is visually inspected through a peep window which is formed in a furnace wall. Both these methods are similar in visually observing the burning flame.
As an automated monitoring method, there has been a method which employs a flame detector. This method, however, uses the flame detector merely for deciding the automatic ignition and extinction of a burner and does not diagnose the combustion state in the furnace. As regards the monitoring of the combustion state during the operation of a boiler, any quantatized diagnostic method has not been established, and it is the present situation that the monitoring is inevitably resorted to the operator's experience and perception.
An example of monitoring having heretofore been performed is described in U.S. Pat. No. 3,824,391 (Methods of and apparatus for flame monitoring; July 16, 1974). This patent concerns methods of and apparatus for monitoring the flame of a furnace including a plurality of burners as in the boiler of a power station. It consists in that the flame of the selected one of the burners of the furnace is photoelectrically monitored by the use of two photosensors, and discloses that signals which have A.C. components corresponding to the intensity fluctuations of radiant rays from the flame are detected by the two sensors and have the degree of their correlation measured. One of the objects of the invention is to monitor the presence of the flame.
A flame scanning method and apparatus are described in Japanese Laid-open Patent Application No. 57-77823 (Flame scanning method and apparatus; May 15, 1982; corresponding to U.S. Ser. No. 185,113, Sep. 8, 1980, now U.S. Pat. No. 4,322,723. This patent application concerns a method of scanning a flame, especially a method of detecting the occurrence of any fault in the sensor or connection cable of a scanning apparatus.
An example of an image sensor usable in the monitoring is described in U.S. Pat. No. 4,176,369 (Image sensor having improved moving target discernment capability; Nov. 27, 1979). The patent, however, consists in the image sensor itself to the last, which is designed so as to discern the variation of an image.
Although the flame monitoring techniques have been developed in this manner, there is not found an example wherein any condition of a flame is grasped so as to diagnose a combustion state in a furnace.